This application relates to an adjustable fan blade wherein the angle of incident of the fan blade may be changed utilizing a piezoelectric actuator.
Gas turbine engines are known, and typically include a fan delivering air into a compressor section. The air is compressed and moved downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over a turbine section, driving turbine rotors to rotate. The turbine rotors in turn rotate the compressor rotors and the fan.
Traditionally, a turbine rotor drove a compressor rotor and the fan rotor at one speed. However, more recently, a gear reduction has been incorporated between the turbine rotor and the fan such that the fan can rotate at a lower speed than the turbine rotor. This has resulted in a great deal of design freedom for the fan.
It has become desirable to make the fan rotor and blades much larger radially. The fan typically delivers a portion of air into a bypass duct as propulsion air along with the air that is delivered into the compressor.
For any number of reasons it becomes desirable to adjust the pitch of the fan blades such that they may be at different angles during different periods of operation. An adjustment ring has typically been rotated, and as it rotates it cams the fan blades to change their angle. Historically, electric motors, or other relatively large mechanical actuators have been utilized.